// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

use std::{
    cmp,
    collections::{BTreeMap, BTreeSet, HashSet},
    sync::Arc,
    time::{Duration, Instant},
};

use ansi_term::Colour;
use bytes::Bytes;
use call_contract::CallContract;
#[cfg(feature = "work-notify")]
use ethcore_miner::work_notify::NotifyWork;
use ethcore_miner::{
    gas_pricer::GasPricer,
    local_accounts::LocalAccounts,
    pool::{
        self,
        transaction_filter::{match_filter, TransactionFilter},
        PrioritizationStrategy, QueueStatus, TransactionQueue, VerifiedTransaction,
    },
    service_transaction_checker::ServiceTransactionChecker,
};
use ethereum_types::{Address, H256, U256};
use io::IoChannel;
use miner::{
    self,
    pool_client::{CachedNonceClient, NonceCache, PoolClient},
    MinerService,
};
use parking_lot::{Mutex, RwLock};
use rayon::prelude::*;
use types::{
    block::Block,
    header::Header,
    receipt::RichReceipt,
    transaction::{self, Action, PendingTransaction, SignedTransaction, UnverifiedTransaction},
    BlockNumber,
};
use using_queue::{GetAction, UsingQueue};

use block::{ClosedBlock, SealedBlock};
use client::{
    traits::{EngineClient, ForceUpdateSealing},
    BlockChain, BlockId, BlockProducer, ChainInfo, ClientIoMessage, Nonce, SealedBlockImporter,
    TransactionId, TransactionInfo,
};
use engines::{EngineSigner, EthEngine, Seal, SealingState};
use error::{Error, ErrorKind};
use executed::ExecutionError;
use executive::contract_address;
use spec::Spec;
use state::State;

/// Different possible definitions for pending transaction set.
#[derive(Debug, PartialEq)]
pub enum PendingSet {
    /// Always just the transactions in the queue. These have had only cheap checks.
    AlwaysQueue,
    /// Always just the transactions in the sealing block. These have had full checks but
    /// may be empty if the node is not actively mining or has no force_sealing enabled.
    AlwaysSealing,
    /// Takes from sealing if mining, from queue otherwise.
    SealingOrElseQueue,
}

/// Transaction queue penalization settings.
///
/// Senders of long-running transactions (above defined threshold)
/// will get lower priority.
#[derive(Debug, PartialEq, Clone)]
pub enum Penalization {
    /// Penalization in transaction queue is disabled
    Disabled,
    /// Penalization in transaction queue is enabled
    Enabled {
        /// Upper limit of transaction processing time before penalizing.
        offend_threshold: Duration,
    },
}

/// Pending block preparation status.
#[derive(Debug, PartialEq)]
pub enum BlockPreparationStatus {
    /// We had to prepare new pending block and the preparation succeeded.
    Succeeded,
    /// We had to prepare new pending block but the preparation failed.
    Failed,
    /// We didn't have to prepare a new block.
    NotPrepared,
}

/// Initial minimal gas price.
///
/// Gas price should be later overwritten externally
/// for instance by a dynamic gas price mechanism or CLI parameter.
/// This constant controls the initial value.
const DEFAULT_MINIMAL_GAS_PRICE: u64 = 20_000_000_000;

/// Allowed number of skipped transactions when constructing pending block.
///
/// When we push transactions to pending block, some of the transactions might
/// get skipped because of block gas limit being reached.
/// This constant controls how many transactions we can skip because of that
/// before stopping attempts to push more transactions to the block.
/// This is an optimization that prevents traversing the entire pool
/// in case we have only a fraction of available block gas limit left.
const MAX_SKIPPED_TRANSACTIONS: usize = 128;

/// Configures the behaviour of the miner.
#[derive(Debug, PartialEq)]
pub struct MinerOptions {
    /// Force the miner to reseal, even when nobody has asked for work.
    pub force_sealing: bool,
    /// Reseal on receipt of new external transactions.
    pub reseal_on_external_tx: bool,
    /// Reseal on receipt of new local transactions.
    pub reseal_on_own_tx: bool,
    /// Reseal when new uncle block has been imported.
    pub reseal_on_uncle: bool,
    /// Minimum period between transaction-inspired reseals.
    pub reseal_min_period: Duration,
    /// Maximum period between blocks (enables force sealing after that).
    pub reseal_max_period: Duration,
    /// Whether we should fallback to providing all the queue's transactions or just pending.
    pub pending_set: PendingSet,
    /// How many historical work packages can we store before running out?
    pub work_queue_size: usize,
    /// Can we submit two different solutions for the same block and expect both to result in an import?
    pub enable_resubmission: bool,
    /// Create a pending block with maximal possible gas limit.
    /// NOTE: Such block will contain all pending transactions but
    /// will be invalid if mined.
    pub infinite_pending_block: bool,

    /// Strategy to use for prioritizing transactions in the queue.
    pub tx_queue_strategy: PrioritizationStrategy,
    /// Simple senders penalization.
    pub tx_queue_penalization: Penalization,
    /// Do we want to mark transactions recieved locally (e.g. RPC) as local if we don't have the sending account?
    pub tx_queue_no_unfamiliar_locals: bool,
    /// Do we refuse to accept service transactions even if sender is certified.
    pub refuse_service_transactions: bool,
    /// Transaction pool limits.
    pub pool_limits: pool::Options,
    /// Initial transaction verification options.
    pub pool_verification_options: pool::verifier::Options,
}

impl Default for MinerOptions {
    fn default() -> Self {
        MinerOptions {
            force_sealing: false,
            reseal_on_external_tx: false,
            reseal_on_own_tx: true,
            reseal_on_uncle: false,
            reseal_min_period: Duration::from_secs(2),
            reseal_max_period: Duration::from_secs(120),
            pending_set: PendingSet::AlwaysQueue,
            work_queue_size: 20,
            enable_resubmission: true,
            infinite_pending_block: false,
            tx_queue_strategy: PrioritizationStrategy::GasPriceOnly,
            tx_queue_penalization: Penalization::Disabled,
            tx_queue_no_unfamiliar_locals: false,
            refuse_service_transactions: false,
            pool_limits: pool::Options {
                max_count: 8_192,
                max_per_sender: 81,
                max_mem_usage: 4 * 1024 * 1024,
            },
            pool_verification_options: pool::verifier::Options {
                minimal_gas_price: DEFAULT_MINIMAL_GAS_PRICE.into(),
                block_gas_limit: U256::max_value(),
                block_base_fee: None,
                tx_gas_limit: U256::max_value(),
                no_early_reject: false,
            },
        }
    }
}

/// Configurable parameters of block authoring.
#[derive(Debug, Default, Clone)]
pub struct AuthoringParams {
    /// Lower and upper bound of block gas limit that we are targeting
    pub gas_range_target: (U256, U256),
    /// Block author
    pub author: Address,
    /// Block extra data
    pub extra_data: Bytes,
}

/// Block sealing mechanism
pub enum Author {
    /// Sealing block is external and we only need a reward beneficiary (i.e. PoW)
    External(Address),
    /// Sealing is done internally, we need a way to create signatures to seal block (i.e. PoA)
    Sealer(Box<dyn EngineSigner>),
}

impl Author {
    /// Get author's address.
    pub fn address(&self) -> Address {
        match *self {
            Author::External(address) => address,
            Author::Sealer(ref sealer) => sealer.address(),
        }
    }
}

struct SealingWork {
    queue: UsingQueue<ClosedBlock>,
    enabled: bool,
    next_allowed_reseal: Instant,
    next_mandatory_reseal: Instant,
    // block number when sealing work was last requested
    last_request: Option<u64>,
}

impl SealingWork {
    /// Are we allowed to do a non-mandatory reseal?
    fn reseal_allowed(&self) -> bool {
        Instant::now() > self.next_allowed_reseal
    }
}

/// Keeps track of transactions using priority queue and holds currently mined block.
/// Handles preparing work for "work sealing" or seals "internally" if Engine does not require work.
pub struct Miner {
    // NOTE [ToDr]  When locking always lock in this order!
    sealing: Mutex<SealingWork>,
    params: RwLock<AuthoringParams>,
    #[cfg(feature = "work-notify")]
    listeners: RwLock<Vec<Box<dyn NotifyWork>>>,
    nonce_cache: NonceCache,
    gas_pricer: Mutex<GasPricer>,
    options: MinerOptions,
    // TODO [ToDr] Arc is only required because of price updater
    transaction_queue: Arc<TransactionQueue>,
    engine: Arc<dyn EthEngine>,
    accounts: Arc<dyn LocalAccounts>,
    io_channel: RwLock<Option<IoChannel<ClientIoMessage>>>,
    service_transaction_checker: Option<ServiceTransactionChecker>,
}

impl Miner {
    /// Push listener that will handle new jobs
    #[cfg(feature = "work-notify")]
    pub fn add_work_listener(&self, notifier: Box<dyn NotifyWork>) {
        self.listeners.write().push(notifier);
        self.sealing.lock().enabled = true;
    }

    /// Set a callback to be notified about imported transactions' hashes.
    pub fn add_transactions_listener(&self, f: Box<dyn Fn(&[H256]) + Send + Sync>) {
        self.transaction_queue.add_listener(f);
    }

    /// Creates new instance of miner Arc.
    pub fn new<A: LocalAccounts + 'static>(
        options: MinerOptions,
        gas_pricer: GasPricer,
        spec: &Spec,
        accounts: A,
    ) -> Self {
        let limits = options.pool_limits.clone();
        let verifier_options = options.pool_verification_options.clone();
        let tx_queue_strategy = options.tx_queue_strategy;
        let nonce_cache_size = cmp::max(4096, limits.max_count / 4);
        let refuse_service_transactions = options.refuse_service_transactions;
        let engine = spec.engine.clone();

        Miner {
            sealing: Mutex::new(SealingWork {
                queue: UsingQueue::new(options.work_queue_size),
                enabled: options.force_sealing
                    || spec.engine.sealing_state() != SealingState::External,
                next_allowed_reseal: Instant::now(),
                next_mandatory_reseal: Instant::now() + options.reseal_max_period,
                last_request: None,
            }),
            params: RwLock::new(AuthoringParams::default()),
            #[cfg(feature = "work-notify")]
            listeners: RwLock::new(vec![]),
            gas_pricer: Mutex::new(gas_pricer),
            nonce_cache: NonceCache::new(nonce_cache_size),
            options,
            transaction_queue: Arc::new(TransactionQueue::new(
                limits,
                verifier_options,
                tx_queue_strategy,
            )),
            accounts: Arc::new(accounts),
            engine,
            io_channel: RwLock::new(None),
            service_transaction_checker: if refuse_service_transactions {
                None
            } else {
                Some(ServiceTransactionChecker::default())
            },
        }
    }

    /// Creates new instance of miner with given spec and accounts.
    ///
    /// NOTE This should be only used for tests.
    pub fn new_for_tests(spec: &Spec, accounts: Option<HashSet<Address>>) -> Miner {
        Miner::new_for_tests_force_sealing(spec, accounts, false)
    }

    /// Creates new instance of miner with given spec and accounts.
    ///
    /// NOTE This should be only used for tests.
    pub fn new_for_tests_force_sealing(
        spec: &Spec,
        accounts: Option<HashSet<Address>>,
        force_sealing: bool,
    ) -> Miner {
        let minimal_gas_price = 0.into();
        Miner::new(
            MinerOptions {
                pool_verification_options: pool::verifier::Options {
                    minimal_gas_price,
                    block_gas_limit: U256::max_value(),
                    block_base_fee: None,
                    tx_gas_limit: U256::max_value(),
                    no_early_reject: false,
                },
                reseal_min_period: Duration::from_secs(0),
                force_sealing,
                ..Default::default()
            },
            GasPricer::new_fixed(minimal_gas_price),
            spec,
            accounts.unwrap_or_default(),
        )
    }

    /// Sets `IoChannel`
    pub fn set_io_channel(&self, io_channel: IoChannel<ClientIoMessage>) {
        *self.io_channel.write() = Some(io_channel);
    }

    /// Sets in-blockchain checker for transactions.
    pub fn set_in_chain_checker<C>(&self, chain: &Arc<C>)
    where
        C: TransactionInfo + Send + Sync + 'static,
    {
        let client = Arc::downgrade(chain);
        self.transaction_queue
            .set_in_chain_checker(move |hash| match client.upgrade() {
                Some(info) => info.transaction_block(TransactionId::Hash(*hash)).is_some(),
                None => false,
            });
    }

    /// Clear all pending block states
    pub fn clear(&self) {
        self.sealing.lock().queue.reset();
    }

    /// Updates transaction queue verification limits.
    ///
    /// Limits consist of current block gas limit and minimal gas price.
    pub fn update_transaction_queue_limits(
        &self,
        block_gas_limit: U256,
        block_base_fee: Option<U256>,
    ) {
        trace!(target: "miner", "minimal_gas_price: recalibrating...");
        let txq = self.transaction_queue.clone();
        let mut options = self.options.pool_verification_options.clone();
        self.gas_pricer.lock().recalibrate(move |gas_price| {
            debug!(target: "miner", "minimal_gas_price: Got gas price! {}", gas_price);
            options.minimal_gas_price = gas_price;
            options.block_gas_limit = block_gas_limit;
            options.block_base_fee = block_base_fee;
            txq.set_verifier_options(options);
        });

        match block_base_fee {
            Some(block_base_fee) => self.transaction_queue.update_scoring(block_base_fee),
            None => (),
        }
    }

    /// Returns ServiceTransactionChecker
    pub fn service_transaction_checker(&self) -> Option<ServiceTransactionChecker> {
        self.service_transaction_checker.clone()
    }

    /// Retrieves an existing pending block iff it's not older than given block number.
    ///
    /// NOTE: This will not prepare a new pending block if it's not existing.
    fn map_existing_pending_block<F, T>(&self, f: F, latest_block_number: BlockNumber) -> Option<T>
    where
        F: FnOnce(&ClosedBlock) -> T,
    {
        self.sealing.lock().queue.peek_last_ref().and_then(|b| {
            // to prevent a data race between block import and updating pending block
            // we allow the number to be equal.
            if b.header.number() >= latest_block_number {
                Some(f(b))
            } else {
                None
            }
        })
    }

    fn pool_client<'a, C: 'a>(&'a self, chain: &'a C) -> PoolClient<'a, C>
    where
        C: BlockChain + CallContract,
    {
        PoolClient::new(
            chain,
            &self.nonce_cache,
            &*self.engine,
            &*self.accounts,
            self.service_transaction_checker.as_ref(),
        )
    }

    /// Prepares new block for sealing including top transactions from queue.
    fn prepare_block<C>(&self, chain: &C) -> Option<(ClosedBlock, Option<H256>)>
    where
        C: BlockChain + CallContract + BlockProducer + Nonce + Sync,
    {
        trace_time!("prepare_block");
        let chain_info = chain.chain_info();

        // Some engines add transactions to the block for their own purposes, e.g. AuthorityRound RANDAO.
        let (mut open_block, original_work_hash, engine_txs) = {
            let mut sealing = self.sealing.lock();
            let last_work_hash = sealing.queue.peek_last_ref().map(|pb| pb.header.hash());
            let best_hash = chain_info.best_block_hash;

            // check to see if last ClosedBlock in would_seals is actually same parent block.
            // if so
            //   duplicate, re-open and push any new transactions.
            //   if at least one was pushed successfully, close and enqueue new ClosedBlock;
            //   otherwise, leave everything alone.
            // otherwise, author a fresh block.
            match sealing
                .queue
                .get_pending_if(|b| b.header.parent_hash() == &best_hash)
            {
                Some(old_block) => {
                    trace!(target: "miner", "prepare_block: Already have previous work; updating and returning");
                    // add transactions to old_block
                    (chain.reopen_block(old_block), last_work_hash, Vec::new())
                }
                None => {
                    // block not found - create it.
                    trace!(target: "miner", "prepare_block: No existing work - making new block");
                    let params = self.params.read().clone();

                    let block = match chain.prepare_open_block(
                        params.author,
                        params.gas_range_target,
                        params.extra_data,
                    ) {
                        Ok(block) => block,
                        Err(err) => {
                            warn!(target: "miner", "Open new block failed with error {:?}. This is likely an error in \
								  chain specification or on-chain consensus smart contracts.", err);
                            return None;
                        }
                    };
                    // Before adding from the queue to the new block, give the engine a chance to add transactions.
                    match self.engine.generate_engine_transactions(&block) {
                        Ok(transactions) => (block, last_work_hash, transactions),
                        Err(err) => {
                            error!(target: "miner", "Failed to prepare engine transactions for new block: {:?}. \
								   This is likely an error in chain specification or on-chain consensus smart \
								   contracts.", err);
                            return None;
                        }
                    }
                }
            }
        };

        if self.options.infinite_pending_block {
            open_block.remove_gas_limit();
        }

        let mut invalid_transactions = HashSet::new();
        let mut not_allowed_transactions = HashSet::new();
        let mut senders_to_penalize = HashSet::new();
        let block_number = open_block.header.number();

        let mut tx_count = 0usize;
        let mut skipped_transactions = 0usize;

        let client = self.pool_client(chain);
        let engine_params = self.engine.params();
        let schedule = self.engine.schedule(block_number);
        let min_tx_gas: U256 = schedule.tx_gas.into();
        let gas_limit = open_block.header.gas_limit();
        let nonce_cap: Option<U256> = if chain_info.best_block_number + 1
            >= engine_params.dust_protection_transition
        {
            Some((engine_params.nonce_cap_increment * (chain_info.best_block_number + 1)).into())
        } else {
            None
        };
        // we will never need more transactions than limit divided by min gas
        let max_transactions = if min_tx_gas.is_zero() {
            usize::max_value()
        } else {
            MAX_SKIPPED_TRANSACTIONS.saturating_add(
                cmp::min(gas_limit / min_tx_gas, u64::max_value().into()).as_u64() as usize,
            )
        };

        let queue_txs: Vec<Arc<_>> = self.transaction_queue.pending(
            client.clone(),
            pool::PendingSettings {
                block_number: chain_info.best_block_number,
                current_timestamp: chain_info.best_block_timestamp,
                nonce_cap,
                max_len: max_transactions.saturating_sub(engine_txs.len()),
                ordering: miner::PendingOrdering::Priority,
                includable_boundary: self
                    .engine
                    .calculate_base_fee(&chain.best_block_header())
                    .unwrap_or_default(),
            },
        );

        let took_ms = |elapsed: &Duration| {
            elapsed.as_secs() * 1000 + elapsed.subsec_nanos() as u64 / 1_000_000
        };

        let block_start = Instant::now();
        debug!(target: "miner", "Attempting to push {} transactions.", engine_txs.len() + queue_txs.len());

        for transaction in engine_txs
            .into_iter()
            .chain(queue_txs.into_iter().map(|tx| tx.signed().clone()))
        {
            let start = Instant::now();

            let hash = transaction.hash();
            let sender = transaction.sender();

            // Re-verify transaction again vs current state.
            let result = client
                .verify_for_pending_block(&transaction, &open_block.header)
                .map_err(|e| e.into())
                .and_then(|_| open_block.push_transaction(transaction, None));

            let took = start.elapsed();

            // Check for heavy transactions
            match self.options.tx_queue_penalization {
                Penalization::Enabled {
                    ref offend_threshold,
                } if &took > offend_threshold => {
                    senders_to_penalize.insert(sender);
                    debug!(target: "miner", "Detected heavy transaction ({} ms). Penalizing sender.", took_ms(&took));
                }
                _ => {}
            }

            debug!(target: "miner", "Adding tx {:?} took {} ms", hash, took_ms(&took));
            match result {
                Err(Error(
                    ErrorKind::Execution(ExecutionError::BlockGasLimitReached {
                        gas_limit,
                        gas_used,
                        gas,
                    }),
                    _,
                )) => {
                    debug!(target: "miner", "Skipping adding transaction to block because of gas limit: {:?} (limit: {:?}, used: {:?}, gas: {:?})", hash, gas_limit, gas_used, gas);

                    // Penalize transaction if it's above current gas limit
                    if gas > gas_limit {
                        debug!(target: "txqueue", "[{:?}] Transaction above block gas limit.", hash);
                        invalid_transactions.insert(hash);
                    }

                    // Exit early if gas left is smaller then min_tx_gas
                    let gas_left = gas_limit - gas_used;
                    if gas_left < min_tx_gas {
                        debug!(target: "miner", "Remaining gas is lower than minimal gas for a transaction. Block is full.");
                        break;
                    }

                    // Avoid iterating over the entire queue in case block is almost full.
                    skipped_transactions += 1;
                    if skipped_transactions > MAX_SKIPPED_TRANSACTIONS {
                        debug!(target: "miner", "Reached skipped transactions threshold. Assuming block is full.");
                        break;
                    }
                }
                // Invalid nonce error can happen only if previous transaction is skipped because of gas limit.
                // If there is errornous state of transaction queue it will be fixed when next block is imported.
                Err(Error(
                    ErrorKind::Execution(ExecutionError::InvalidNonce { expected, got }),
                    _,
                )) => {
                    debug!(target: "miner", "Skipping adding transaction to block because of invalid nonce: {:?} (expected: {:?}, got: {:?})", hash, expected, got);
                }
                // already have transaction - ignore
                Err(Error(ErrorKind::Transaction(transaction::Error::AlreadyImported), _)) => {}
                Err(Error(ErrorKind::Transaction(transaction::Error::NotAllowed), _)) => {
                    not_allowed_transactions.insert(hash);
                    debug!(target: "miner", "Skipping non-allowed transaction for sender {:?}", hash);
                }
                Err(e) => {
                    debug!(target: "txqueue", "[{:?}] Marking as invalid: {:?}.", hash, e);
                    debug!(
                        target: "miner", "Error adding transaction to block: number={}. transaction_hash={:?}, Error: {:?}", block_number, hash, e
                    );
                    invalid_transactions.insert(hash);
                }
                // imported ok
                _ => tx_count += 1,
            }
        }
        let elapsed = block_start.elapsed();
        debug!(target: "miner", "Pushed {} transactions in {} ms", tx_count, took_ms(&elapsed));

        let block = match open_block.close() {
            Ok(block) => block,
            Err(err) => {
                warn!(target: "miner", "Closing the block failed with error {:?}. This is likely an error in chain specificiations or on-chain consensus smart contracts.", err);
                return None;
            }
        };

        {
            self.transaction_queue
                .remove(invalid_transactions.iter(), true);
            self.transaction_queue
                .remove(not_allowed_transactions.iter(), false);
            self.transaction_queue.penalize(senders_to_penalize.iter());
        }

        Some((block, original_work_hash))
    }

    /// Returns `true` if we should create pending block even if some other conditions are not met.
    ///
    /// In general we always seal iff:
    /// 1. --force-sealing CLI parameter is provided
    /// 2. There are listeners awaiting new work packages (e.g. remote work notifications or stratum).
    fn forced_sealing(&self) -> bool {
        let listeners_empty = {
            #[cfg(feature = "work-notify")]
            {
                self.listeners.read().is_empty()
            }
            #[cfg(not(feature = "work-notify"))]
            {
                true
            }
        };

        self.options.force_sealing || !listeners_empty
    }

    /// Check is reseal is allowed and necessary.
    fn requires_reseal(&self, best_block: BlockNumber) -> bool {
        let mut sealing = self.sealing.lock();
        if !sealing.enabled {
            trace!(target: "miner", "requires_reseal: sealing is disabled");
            return false;
        }

        if !sealing.reseal_allowed() {
            trace!(target: "miner", "requires_reseal: reseal too early");
            return false;
        }

        trace!(target: "miner", "requires_reseal: sealing enabled");

        // Disable sealing if there were no requests for SEALING_TIMEOUT_IN_BLOCKS
        let had_requests = sealing
            .last_request
            .map(|last_request| {
                best_block.saturating_sub(last_request) <= SEALING_TIMEOUT_IN_BLOCKS
            })
            .unwrap_or(false);

        // keep sealing enabled if any of the conditions is met
        let sealing_enabled = self.forced_sealing()
            || self.transaction_queue.has_local_pending_transactions()
            || self.engine.sealing_state() == SealingState::Ready
            || had_requests;

        let should_disable_sealing = !sealing_enabled;

        trace!(target: "miner", "requires_reseal: should_disable_sealing={}; forced={:?}, has_local={:?}, internal={:?}, had_requests={:?}",
            should_disable_sealing,
            self.forced_sealing(),
            self.transaction_queue.has_local_pending_transactions(),
            self.engine.sealing_state(),
            had_requests,
        );

        if should_disable_sealing {
            trace!(target: "miner", "Miner sleeping (current {}, last {})", best_block, sealing.last_request.unwrap_or(0));
            sealing.enabled = false;
            sealing.queue.reset();
            false
        } else {
            // sealing enabled and we don't want to sleep.
            sealing.next_allowed_reseal = Instant::now() + self.options.reseal_min_period;
            true
        }
    }

    // TODO: (https://github.com/openethereum/openethereum/issues/10407)
    // This is only used in authority_round path, and should be refactored to merge with the other seal() path.
    // Attempts to perform internal sealing (one that does not require work) and handles the result depending on the
    // type of Seal.
    fn seal_and_import_block_internally<C>(&self, chain: &C, block: ClosedBlock) -> bool
    where
        C: BlockChain + SealedBlockImporter,
    {
        {
            let sealing = self.sealing.lock();
            if block.transactions.is_empty()
                && !self.forced_sealing()
                && Instant::now() <= sealing.next_mandatory_reseal
            {
                return false;
            }
        }

        trace!(target: "miner", "seal_block_internally: attempting internal seal.");

        let parent_header = match chain.block_header(BlockId::Hash(*block.header.parent_hash())) {
            Some(h) => match h.decode(self.engine.params().eip1559_transition) {
                Ok(decoded_hdr) => decoded_hdr,
                Err(_) => return false,
            },
            None => return false,
        };

        match self.engine.generate_seal(&block, &parent_header) {
            // Save proposal for later seal submission and broadcast it.
            Seal::Proposal(seal) => {
                trace!(target: "miner", "Received a Proposal seal.");
                {
                    let mut sealing = self.sealing.lock();
                    sealing.next_mandatory_reseal = Instant::now() + self.options.reseal_max_period;
                    sealing.queue.set_pending(block.clone());
                    sealing.queue.use_last_ref();
                }

                block
                    .lock()
                    .seal(&*self.engine, seal)
                    .map(|sealed| {
                        chain.broadcast_proposal_block(sealed);
                        true
                    })
                    .unwrap_or_else(|e| {
                        warn!(
                            "ERROR: seal failed when given internally generated seal: {}",
                            e
                        );
                        false
                    })
            }
            // Directly import a regular sealed block.
            Seal::Regular(seal) => {
                trace!(target: "miner", "Received a Regular seal.");
                {
                    let mut sealing = self.sealing.lock();
                    sealing.next_mandatory_reseal = Instant::now() + self.options.reseal_max_period;
                }

                block
                    .lock()
                    .seal(&*self.engine, seal)
                    .map(|sealed| chain.import_sealed_block(sealed).is_ok())
                    .unwrap_or_else(|e| {
                        warn!(
                            "ERROR: seal failed when given internally generated seal: {}",
                            e
                        );
                        false
                    })
            }
            Seal::None => false,
        }
    }

    /// Prepares work which has to be done to seal.
    fn prepare_work(&self, block: ClosedBlock, original_work_hash: Option<H256>) {
        let (work, is_new) = {
            let block_header = block.header.clone();
            let block_hash = block_header.hash();

            let mut sealing = self.sealing.lock();
            let last_work_hash = sealing.queue.peek_last_ref().map(|pb| pb.header.hash());

            trace!(
                target: "miner",
                "prepare_work: Checking whether we need to reseal: orig={:?} last={:?}, this={:?}",
                original_work_hash, last_work_hash, block_hash
            );

            let (work, is_new) = if last_work_hash.map_or(true, |h| h != block_hash) {
                trace!(
                    target: "miner",
                    "prepare_work: Pushing a new, refreshed or borrowed pending {}...",
                    block_hash
                );
                let is_new = original_work_hash.map_or(true, |h| h != block_hash);

                sealing.queue.set_pending(block);

                #[cfg(feature = "work-notify")]
                {
                    // If push notifications are enabled we assume all work items are used.
                    if is_new && !self.listeners.read().is_empty() {
                        sealing.queue.use_last_ref();
                    }
                }

                (
                    Some((
                        block_hash,
                        *block_header.difficulty(),
                        block_header.number(),
                    )),
                    is_new,
                )
            } else {
                (None, false)
            };
            trace!(
                target: "miner",
                "prepare_work: leaving (last={:?})",
                sealing.queue.peek_last_ref().map(|b| b.header.hash())
            );
            (work, is_new)
        };

        #[cfg(feature = "work-notify")]
        {
            if is_new {
                work.map(|(pow_hash, difficulty, number)| {
                    for notifier in self.listeners.read().iter() {
                        notifier.notify(pow_hash, difficulty, number)
                    }
                });
            }
        }

        // NB: hack to use variables to avoid warning.
        #[cfg(not(feature = "work-notify"))]
        {
            let _work = work;
            let _is_new = is_new;
        }
    }

    /// Prepare a pending block. Returns the preparation status.
    fn prepare_pending_block<C>(&self, client: &C) -> BlockPreparationStatus
    where
        C: BlockChain + CallContract + BlockProducer + SealedBlockImporter + Nonce + Sync,
    {
        trace!(target: "miner", "prepare_pending_block: entering");
        let prepare_new = {
            let mut sealing = self.sealing.lock();
            let have_work = sealing.queue.peek_last_ref().is_some();
            trace!(target: "miner", "prepare_pending_block: have_work={}", have_work);
            if !have_work {
                sealing.enabled = true;
                true
            } else {
                false
            }
        };

        if self.engine.sealing_state() != SealingState::External {
            trace!(target: "miner", "prepare_pending_block: engine not sealing externally; not preparing");
            return BlockPreparationStatus::NotPrepared;
        }

        let preparation_status = if prepare_new {
            // --------------------------------------------------------------------------
            // | NOTE Code below requires sealing locks.                                |
            // | Make sure to release the locks before calling that method.             |
            // --------------------------------------------------------------------------
            match self.prepare_block(client) {
                Some((block, original_work_hash)) => {
                    self.prepare_work(block, original_work_hash);
                    BlockPreparationStatus::Succeeded
                }
                None => BlockPreparationStatus::Failed,
            }
        } else {
            BlockPreparationStatus::NotPrepared
        };

        let best_number = client.chain_info().best_block_number;
        let mut sealing = self.sealing.lock();
        if sealing.last_request != Some(best_number) {
            trace!(
                target: "miner",
                "prepare_pending_block: Miner received request (was {}, now {}) - waking up.",
                sealing.last_request.unwrap_or(0), best_number
            );
            sealing.last_request = Some(best_number);
        }

        preparation_status
    }

    /// Prepare pending block, check whether sealing is needed, and then update sealing.
    fn prepare_and_update_sealing<C: miner::BlockChainClient>(&self, chain: &C) {
        // Make sure to do it after transaction is imported and lock is dropped.
        // We need to create pending block and enable sealing.
        let sealing_state = self.engine.sealing_state();

        if sealing_state == SealingState::Ready
            || self.prepare_pending_block(chain) == BlockPreparationStatus::NotPrepared
        {
            // If new block has not been prepared (means we already had one)
            // or Engine might be able to seal internally,
            // we need to update sealing.
            self.update_sealing(chain, ForceUpdateSealing::No);
        }
    }
}

const SEALING_TIMEOUT_IN_BLOCKS: u64 = 5;

impl miner::MinerService for Miner {
    type State = State<::state_db::StateDB>;

    fn authoring_params(&self) -> AuthoringParams {
        self.params.read().clone()
    }

    fn set_gas_range_target(&self, gas_range_target: (U256, U256)) {
        self.params.write().gas_range_target = gas_range_target;
    }

    fn set_extra_data(&self, extra_data: Bytes) {
        self.params.write().extra_data = extra_data;
    }

    fn set_author<T: Into<Option<Author>>>(&self, author: T) {
        let author_opt = author.into();
        self.params.write().author = author_opt.as_ref().map(Author::address).unwrap_or_default();

        match author_opt {
            Some(Author::Sealer(signer)) => {
                if self.engine.sealing_state() != SealingState::External {
                    // Enable sealing
                    self.sealing.lock().enabled = true;
                    // --------------------------------------------------------------------------
                    // | NOTE Code below may require author and sealing locks                   |
                    // | (some `Engine`s call `EngineClient.update_sealing()`)                  |
                    // | Make sure to release the locks before calling that method.             |
                    // --------------------------------------------------------------------------
                    self.engine.set_signer(Some(signer));
                } else {
                    warn!("Setting an EngineSigner while Engine does not require one.");
                }
            }
            Some(Author::External(_address)) => (),
            None => {
                // Clear the author.
                if self.engine.sealing_state() != SealingState::External {
                    // Disable sealing.
                    self.sealing.lock().enabled = false;
                    // --------------------------------------------------------------------------
                    // | NOTE Code below may require author and sealing locks                   |
                    // | (some `Engine`s call `EngineClient.update_sealing()`)                  |
                    // | Make sure to release the locks before calling that method.             |
                    // --------------------------------------------------------------------------
                    self.engine.set_signer(None);
                }
            }
        }
    }

    fn sensible_gas_price(&self) -> U256 {
        // 10% above our minimum.
        self.transaction_queue.current_worst_gas_price() * 110u32 / 100
    }

    fn sensible_gas_limit(&self) -> U256 {
        self.params.read().gas_range_target.0 / 5
    }

    fn set_minimal_gas_price(&self, new_price: U256) -> Result<bool, &str> {
        match *self.gas_pricer.lock() {
            // Binding the gas pricer to `gp` here to prevent
            // a deadlock when calling recalibrate()
            ref mut gp @ GasPricer::Fixed(_) => {
                trace!(target: "miner", "minimal_gas_price: recalibrating fixed...");
                *gp = GasPricer::new_fixed(new_price);

                let txq = self.transaction_queue.clone();
                let mut options = self.options.pool_verification_options.clone();
                gp.recalibrate(move |gas_price| {
                    debug!(target: "miner", "minimal_gas_price: Got gas price! {}", gas_price);
                    options.minimal_gas_price = gas_price;
                    txq.set_verifier_options(options);
                });

                Ok(true)
            }
            #[cfg(feature = "price-info")]
            GasPricer::Calibrated(_) => {
                let error_msg =
                    "Can't update fixed gas price while automatic gas calibration is enabled.";
                return Err(error_msg);
            }
        }
    }

    fn import_external_transactions<C: miner::BlockChainClient>(
        &self,
        chain: &C,
        transactions: Vec<UnverifiedTransaction>,
    ) -> Vec<Result<(), transaction::Error>> {
        trace!(target: "external_tx", "Importing external transactions");
        let client = self.pool_client(chain);
        let results = self.transaction_queue.import(
            client,
            transactions
                .into_iter()
                .map(pool::verifier::Transaction::Unverified)
                .collect(),
        );

        // --------------------------------------------------------------------------
        // | NOTE Code below requires sealing locks.                                |
        // | Make sure to release the locks before calling that method.             |
        // --------------------------------------------------------------------------
        if !results.is_empty()
            && self.options.reseal_on_external_tx
            && self.sealing.lock().reseal_allowed()
        {
            self.prepare_and_update_sealing(chain);
        }

        results
    }

    fn import_own_transaction<C: miner::BlockChainClient>(
        &self,
        chain: &C,
        pending: PendingTransaction,
    ) -> Result<(), transaction::Error> {
        // note: you may want to use `import_claimed_local_transaction` instead of this one.

        trace!(target: "own_tx", "Importing transaction: {:?}", pending);

        let client = self.pool_client(chain);
        let imported = self
            .transaction_queue
            .import(client, vec![pool::verifier::Transaction::Local(pending)])
            .pop()
            .expect("one result returned per added transaction; one added => one result; qed");

        // --------------------------------------------------------------------------
        // | NOTE Code below requires sealing locks.                                |
        // | Make sure to release the locks before calling that method.             |
        // --------------------------------------------------------------------------
        if imported.is_ok() && self.options.reseal_on_own_tx && self.sealing.lock().reseal_allowed()
        {
            self.prepare_and_update_sealing(chain);
        }

        imported
    }

    fn import_claimed_local_transaction<C: miner::BlockChainClient>(
        &self,
        chain: &C,
        pending: PendingTransaction,
        trusted: bool,
    ) -> Result<(), transaction::Error> {
        // treat the tx as local if the option is enabled, if we have the account, or if
        // the account is specified as a Prioritized Local Addresses
        let sender = pending.sender();
        let treat_as_local = trusted
            || !self.options.tx_queue_no_unfamiliar_locals
            || self.accounts.is_local(&sender);

        if treat_as_local {
            self.import_own_transaction(chain, pending)
        } else {
            // We want to replicate behaviour for external transactions if we're not going to treat
            // this as local. This is important with regards to sealing blocks
            self.import_external_transactions(chain, vec![pending.transaction.into()])
                .pop()
                .expect("one result per tx, as in `import_own_transaction`")
        }
    }

    fn local_transactions(&self) -> BTreeMap<H256, pool::local_transactions::Status> {
        self.transaction_queue.local_transactions()
    }

    fn queued_transactions(&self) -> Vec<Arc<VerifiedTransaction>> {
        self.transaction_queue.all_transactions()
    }

    fn queued_transaction_hashes(&self) -> Vec<H256> {
        self.transaction_queue.all_transaction_hashes()
    }

    fn pending_transaction_hashes<C>(&self, chain: &C) -> BTreeSet<H256>
    where
        C: ChainInfo + Sync,
    {
        let chain_info = chain.chain_info();

        let from_queue = || {
            self.transaction_queue
                .pending_hashes(|sender| self.nonce_cache.get(sender))
        };

        let from_pending = || {
            self.map_existing_pending_block(
                |sealing| {
                    sealing
                        .transactions
                        .iter()
                        .map(|signed| signed.hash())
                        .collect()
                },
                chain_info.best_block_number,
            )
        };

        match self.options.pending_set {
            PendingSet::AlwaysQueue => from_queue(),
            PendingSet::AlwaysSealing => from_pending().unwrap_or_default(),
            PendingSet::SealingOrElseQueue => from_pending().unwrap_or_else(from_queue),
        }
    }

    fn ready_transactions_filtered<C>(
        &self,
        chain: &C,
        max_len: usize,
        filter: Option<TransactionFilter>,
        ordering: miner::PendingOrdering,
    ) -> Vec<Arc<VerifiedTransaction>>
    where
        C: BlockChain + Nonce + Sync,
    {
        let chain_info = chain.chain_info();

        let from_queue = || {
            // We propagate transactions over the nonce cap.
            // The mechanism is only to limit number of transactions in pending block
            // those transactions are valid and will just be ready to be included in next block.
            let nonce_cap = None;

            let client = CachedNonceClient::new(chain, &self.nonce_cache);
            let settings = pool::PendingSettings {
                block_number: chain_info.best_block_number,
                current_timestamp: chain_info.best_block_timestamp,
                nonce_cap,
                max_len,
                ordering,
                includable_boundary: self
                    .engine
                    .calculate_base_fee(&chain.best_block_header())
                    .unwrap_or_default(),
            };

            if let Some(ref f) = filter {
                self.transaction_queue.pending_filtered(client, settings, f)
            } else {
                self.transaction_queue.pending(client, settings)
            }
        };

        let from_pending = || {
            self.map_existing_pending_block(
                |sealing| {
                    sealing
                        .transactions
                        .iter()
                        .map(|signed| {
                            pool::VerifiedTransaction::from_pending_block_transaction(
                                signed.clone(),
                            )
                        })
                        .filter(|tx| match_filter(&filter, tx))
                        .map(Arc::new)
                        .take(max_len)
                        .collect()
                },
                chain_info.best_block_number,
            )
        };

        match self.options.pending_set {
            PendingSet::AlwaysQueue => from_queue(),
            PendingSet::AlwaysSealing => from_pending().unwrap_or_default(),
            PendingSet::SealingOrElseQueue => from_pending().unwrap_or_else(from_queue),
        }
    }

    fn next_nonce<C>(&self, chain: &C, address: &Address) -> U256
    where
        C: Nonce + Sync,
    {
        self.transaction_queue
            .next_nonce(CachedNonceClient::new(chain, &self.nonce_cache), address)
            .unwrap_or_else(|| chain.latest_nonce(address))
    }

    fn transaction(&self, hash: &H256) -> Option<Arc<VerifiedTransaction>> {
        self.transaction_queue.find(hash)
    }

    fn remove_transaction(&self, hash: &H256) -> Option<Arc<VerifiedTransaction>> {
        self.transaction_queue
            .remove(::std::iter::once(hash), false)
            .pop()
            .expect("remove() returns one result per hash; one hash passed; qed")
    }

    fn queue_status(&self) -> QueueStatus {
        self.transaction_queue.status()
    }

    fn pending_receipts(&self, best_block: BlockNumber) -> Option<Vec<RichReceipt>> {
        self.map_existing_pending_block(
            |pending| {
                let receipts = &pending.receipts;
                pending
                    .transactions
                    .iter()
                    .enumerate()
                    .map(|(index, tx)| {
                        let prev_gas = if index == 0 {
                            Default::default()
                        } else {
                            receipts[index - 1].gas_used
                        };
                        let receipt = &receipts[index];
                        RichReceipt {
                            from: tx.sender(),
                            to: match tx.tx().action {
                                Action::Create => None,
                                Action::Call(ref address) => Some(*address),
                            },
                            transaction_hash: tx.hash(),
                            transaction_type: tx.tx_type(),
                            transaction_index: index,
                            cumulative_gas_used: receipt.gas_used,
                            gas_used: receipt.gas_used - prev_gas,
                            contract_address: match tx.tx().action {
                                Action::Call(_) => None,
                                Action::Create => {
                                    let sender = tx.sender();
                                    Some(
                                        contract_address(
                                            self.engine
                                                .create_address_scheme(pending.header.number()),
                                            &sender,
                                            &tx.tx().nonce,
                                            &tx.tx().data,
                                        )
                                        .0,
                                    )
                                }
                            },
                            logs: receipt.logs.clone(),
                            log_bloom: receipt.log_bloom,
                            outcome: receipt.outcome.clone(),
                        }
                    })
                    .collect()
            },
            best_block,
        )
    }

    // t_nb 10.4 Update sealing if required.
    /// Prepare the block and work if the Engine does not seal internally.
    fn update_sealing<C>(&self, chain: &C, force: ForceUpdateSealing)
    where
        C: BlockChain + CallContract + BlockProducer + SealedBlockImporter + Nonce + Sync,
    {
        trace!(target: "miner", "update_sealing");

        // Do nothing if we don't want to force update_sealing and reseal is not required.
        // but note that `requires_reseal` updates internal state.
        if force == ForceUpdateSealing::No
            && !self.requires_reseal(chain.chain_info().best_block_number)
        {
            return;
        }

        let sealing_state = self.engine.sealing_state();
        if sealing_state == SealingState::NotReady {
            return;
        }

        // --------------------------------------------------------------------------
        // | NOTE Code below requires sealing locks.                                |
        // | Make sure to release the locks before calling that method.             |
        // --------------------------------------------------------------------------
        trace!(target: "miner", "update_sealing: preparing a block");
        let (block, original_work_hash) = match self.prepare_block(chain) {
            Some((block, original_work_hash)) => (block, original_work_hash),
            None => return,
        };

        // refuse to seal the first block of the chain if it contains hard forks
        // which should be on by default.
        if block.header.number() == 1 {
            if let Some(name) = self.engine.params().nonzero_bugfix_hard_fork() {
                warn!("Your chain specification contains one or more hard forks which are required to be \
						on by default. Please remove these forks and start your chain again: {}.", name);
                return;
            }
        }

        match sealing_state {
            SealingState::Ready => {
                trace!(target: "miner", "update_sealing: engine indicates internal sealing");
                if self.seal_and_import_block_internally(chain, block) {
                    trace!(target: "miner", "update_sealing: imported internally sealed block");
                }
                return;
            }
            SealingState::NotReady => {
                unreachable!("We returned right after sealing_state was computed. qed.")
            }
            //  => {
            //     trace!(target: "miner", "update_sealing: engine is not keen to seal internally right now");
            //     // anyway, save the block for later use
            //     self.sealing.lock().queue.set_pending(block);
            // }
            SealingState::External => {
                trace!(target: "miner", "update_sealing: engine does not seal internally, preparing work");
                self.prepare_work(block, original_work_hash);
            }
        };
    }

    fn is_currently_sealing(&self) -> bool {
        self.sealing.lock().enabled
    }

    fn work_package<C>(&self, chain: &C) -> Option<(H256, BlockNumber, u64, U256)>
    where
        C: BlockChain + CallContract + BlockProducer + SealedBlockImporter + Nonce + Sync,
    {
        if self.engine.sealing_state() != SealingState::External {
            return None;
        }

        self.prepare_pending_block(chain);

        self.sealing.lock().queue.use_last_ref().map(|b| {
            let header = &b.header;
            (
                header.hash(),
                header.number(),
                header.timestamp(),
                *header.difficulty(),
            )
        })
    }

    // Note used for external submission (PoW) and internally by sealing engines.
    fn submit_seal(&self, block_hash: H256, seal: Vec<Bytes>) -> Result<SealedBlock, Error> {
        let result = if let Some(b) = self.sealing.lock().queue.get_used_if(
            if self.options.enable_resubmission {
                GetAction::Clone
            } else {
                GetAction::Take
            },
            |b| &b.header.bare_hash() == &block_hash,
        ) {
            trace!(target: "miner", "Submitted block {}={} with seal {:?}", block_hash, b.header.bare_hash(), seal);
            b.lock().try_seal(&*self.engine, seal).or_else(|e| {
                warn!(target: "miner", "Mined solution rejected: {}", e);
                Err(ErrorKind::PowInvalid.into())
            })
        } else {
            warn!(target: "miner", "Submitted solution rejected: Block unknown or out of date.");
            Err(ErrorKind::PowHashInvalid.into())
        };

        result.and_then(|sealed| {
			let n = sealed.header.number();
			let h = sealed.header.hash();
			info!(target: "miner", "Submitted block imported OK. #{}: {}", Colour::White.bold().paint(format!("{}", n)), Colour::White.bold().paint(format!("{:x}", h)));
			Ok(sealed)
		})
    }

    // t_nb 10 notify miner about new include blocks
    fn chain_new_blocks<C>(
        &self,
        chain: &C,
        imported: &[H256],
        _invalid: &[H256],
        enacted: &[H256],
        retracted: &[H256],
        is_internal_import: bool,
    ) where
        C: miner::BlockChainClient,
    {
        trace!(target: "miner", "chain_new_blocks");

        // 1. We ignore blocks that were `imported` unless resealing on new uncles is enabled.
        // 2. We ignore blocks that are `invalid` because it doesn't have any meaning in terms of the transactions that
        //    are in those blocks

        let has_new_best_block = enacted.len() > 0;

        if has_new_best_block {
            // Clear nonce cache
            self.nonce_cache.clear();
        }

        // t_nb 10.1 First update gas limit in transaction queue and minimal gas price.
        let base_fee = self.engine.calculate_base_fee(&chain.best_block_header());
        let gas_limit = chain.best_block_header().gas_limit()
            // multiplication neccesary only if OE nodes are the only miners in network, not really essential but wont hurt
            *  if self.engine.gas_limit_override(&chain.best_block_header()).is_none() {
                self
                .engine
                .schedule(chain.best_block_header().number() + 1)
                .eip1559_gas_limit_bump
                } else {
                    1
                };
        self.update_transaction_queue_limits(gas_limit, base_fee);

        // t_nb 10.2 Then import all transactions from retracted blocks (retracted means from side chain).
        let client = self.pool_client(chain);
        {
            retracted
				.par_iter()
				.for_each(|hash| {
					let block = chain.block(BlockId::Hash(*hash))
						.expect("Client is sending message after commit to db and inserting to chain; the block is available; qed");
					let txs = block.transactions()
						.into_iter()
						.map(pool::verifier::Transaction::Retracted)
                        .collect();
                    // t_nb 10.2
					let _ = self.transaction_queue.import(
						client.clone(),
						txs,
					);
				});
        }

        if has_new_best_block || (imported.len() > 0 && self.options.reseal_on_uncle) {
            // t_nb 10.3 Reset `next_allowed_reseal` in case a block is imported.
            // Even if min_period is high, we will always attempt to create
            // new pending block.
            self.sealing.lock().next_allowed_reseal = Instant::now();

            if !is_internal_import {
                // t_nb 10.4 if it is internal import update sealing
                // --------------------------------------------------------------------------
                // | NOTE Code below requires sealing locks.                                |
                // | Make sure to release the locks before calling that method.             |
                // --------------------------------------------------------------------------
                self.update_sealing(chain, ForceUpdateSealing::No);
            }
        }

        if has_new_best_block {
            // t_nb 10.5 Make sure to cull transactions after we update sealing.
            // Not culling won't lead to old transactions being added to the block
            // (thanks to Ready), but culling can take significant amount of time,
            // so best to leave it after we create some work for miners to prevent increased
            // uncle rate.
            // If the io_channel is available attempt to offload culling to a separate task
            // to avoid blocking chain_new_blocks
            if let Some(ref channel) = *self.io_channel.read() {
                let queue = self.transaction_queue.clone();
                let nonce_cache = self.nonce_cache.clone();
                let engine = self.engine.clone();
                let accounts = self.accounts.clone();
                let service_transaction_checker = self.service_transaction_checker.clone();

                let cull = move |chain: &::client::Client| {
                    let client = PoolClient::new(
                        chain,
                        &nonce_cache,
                        &*engine,
                        &*accounts,
                        service_transaction_checker.as_ref(),
                    );
                    // t_nb 10.5 do culling
                    queue.cull(client);
                    // reseal is only used by InstaSeal engine
                    if engine.should_reseal_on_update() {
                        // force update_sealing here to skip `reseal_required` checks
                        chain.update_sealing(ForceUpdateSealing::Yes);
                    }
                };

                if let Err(e) = channel.send(ClientIoMessage::execute(cull)) {
                    warn!(target: "miner", "Error queueing cull: {:?}", e);
                }
            } else {
                // t_nb 10.5 do culling
                self.transaction_queue.cull(client);
                // reseal is only used by InstaSeal engine
                if self.engine.should_reseal_on_update() {
                    // force update_sealing here to skip `reseal_required` checks
                    self.update_sealing(chain, ForceUpdateSealing::Yes);
                }
            }
        }
        // t_nb 10.6 For service transaction checker update addresses to latest block
        if let Some(ref service_transaction_checker) = self.service_transaction_checker {
            match service_transaction_checker.refresh_cache(chain) {
                Ok(true) => {
                    trace!(target: "client", "Service transaction cache was refreshed successfully");
                }
                Ok(false) => {
                    trace!(target: "client", "Registrar or/and service transactions contract does not exist");
                }
                Err(e) => {
                    error!(target: "client", "Error occurred while refreshing service transaction cache: {}", e)
                }
            };
        };
    }

    fn pending_state(&self, latest_block_number: BlockNumber) -> Option<Self::State> {
        self.map_existing_pending_block(|b| b.state.clone(), latest_block_number)
    }

    fn pending_block_header(&self, latest_block_number: BlockNumber) -> Option<Header> {
        self.map_existing_pending_block(|b| b.header.clone(), latest_block_number)
    }

    fn pending_block(&self, latest_block_number: BlockNumber) -> Option<Block> {
        self.map_existing_pending_block(
            |b| Block {
                header: b.header.clone(),
                transactions: b.transactions.iter().cloned().map(Into::into).collect(),
                uncles: b.uncles.to_vec(),
            },
            latest_block_number,
        )
    }

    fn pending_transactions(
        &self,
        latest_block_number: BlockNumber,
    ) -> Option<Vec<SignedTransaction>> {
        self.map_existing_pending_block(
            |b| b.transactions.iter().cloned().collect(),
            latest_block_number,
        )
    }
}

#[cfg(test)]
mod tests {
    use std::iter::FromIterator;

    use super::*;
    use accounts::AccountProvider;
    use crypto::publickey::{Generator, Random};
    use hash::keccak;
    use rustc_hex::FromHex;
    use types::BlockNumber;

    use client::{ChainInfo, EachBlockWith, ImportSealedBlock, TestBlockChainClient};
    use miner::{MinerService, PendingOrdering};
    use test_helpers::{generate_dummy_client, generate_dummy_client_with_spec};
    use types::transaction::{Transaction, TypedTransaction};

    #[test]
    fn should_prepare_block_to_seal() {
        // given
        let client = TestBlockChainClient::default();
        let miner = Miner::new_for_tests(&Spec::new_test(), None);

        // when
        let sealing_work = miner.work_package(&client);
        assert!(sealing_work.is_some(), "Expected closed block");
    }

    #[test]
    fn should_still_work_after_a_couple_of_blocks() {
        // given
        let client = TestBlockChainClient::default();
        let miner = Miner::new_for_tests(&Spec::new_test(), None);

        let res = miner.work_package(&client);
        let hash = res.unwrap().0;
        let block = miner.submit_seal(hash, vec![]).unwrap();
        client.import_sealed_block(block).unwrap();

        // two more blocks mined, work requested.
        client.add_blocks(1, EachBlockWith::Uncle);
        miner.work_package(&client);

        client.add_blocks(1, EachBlockWith::Uncle);
        miner.work_package(&client);

        // solution to original work submitted.
        assert!(miner.submit_seal(hash, vec![]).is_ok());
    }

    fn miner() -> Miner {
        Miner::new(
            MinerOptions {
                force_sealing: false,
                reseal_on_external_tx: false,
                reseal_on_own_tx: true,
                reseal_on_uncle: false,
                reseal_min_period: Duration::from_secs(5),
                reseal_max_period: Duration::from_secs(120),
                pending_set: PendingSet::AlwaysSealing,
                work_queue_size: 5,
                enable_resubmission: true,
                infinite_pending_block: false,
                tx_queue_penalization: Penalization::Disabled,
                tx_queue_strategy: PrioritizationStrategy::GasPriceOnly,
                tx_queue_no_unfamiliar_locals: false,
                refuse_service_transactions: false,
                pool_limits: Default::default(),
                pool_verification_options: pool::verifier::Options {
                    minimal_gas_price: 0.into(),
                    block_gas_limit: U256::max_value(),
                    block_base_fee: None,
                    tx_gas_limit: U256::max_value(),
                    no_early_reject: false,
                },
            },
            GasPricer::new_fixed(0u64.into()),
            &Spec::new_test(),
            ::std::collections::HashSet::new(), // local accounts
        )
    }

    const TEST_CHAIN_ID: u64 = 2;

    fn transaction() -> SignedTransaction {
        transaction_with_chain_id(TEST_CHAIN_ID)
    }

    fn transaction_with_chain_id(chain_id: u64) -> SignedTransaction {
        let keypair = Random.generate();
        TypedTransaction::Legacy(Transaction {
            action: Action::Create,
            value: U256::zero(),
            data: "3331600055".from_hex().unwrap(),
            gas: U256::from(100_000),
            gas_price: U256::zero(),
            nonce: U256::zero(),
        })
        .sign(keypair.secret(), Some(chain_id))
    }

    #[test]
    fn should_make_pending_block_when_importing_own_transaction() {
        // given
        let client = TestBlockChainClient::default();
        let miner = miner();
        let transaction = transaction();
        let best_block = 0;
        // when
        let res = miner.import_own_transaction(&client, PendingTransaction::new(transaction, None));

        // then
        assert_eq!(res.unwrap(), ());
        assert_eq!(miner.pending_transactions(best_block).unwrap().len(), 1);
        assert_eq!(miner.pending_receipts(best_block).unwrap().len(), 1);
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            1
        );
        // This method will let us know if pending block was created (before calling that method)
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::NotPrepared
        );
    }

    #[test]
    fn should_not_return_stale_work_packages() {
        // given
        let client = TestBlockChainClient::default();
        let miner = miner();

        // initial work package should create the pending block
        let res = miner.work_package(&client);
        assert_eq!(res.unwrap().1, 1);
        // This should be true, since there were some requests.
        assert_eq!(miner.requires_reseal(0), true);

        // when new block is imported
        let client = generate_dummy_client(2);
        let imported = [H256::zero()];
        let empty = &[];
        miner.chain_new_blocks(&*client, &imported, empty, &imported, empty, false);

        // then
        // This should be false, because it's too early.
        assert_eq!(miner.requires_reseal(2), false);
        // but still work package should be ready
        let res = miner.work_package(&*client);
        assert_eq!(res.unwrap().1, 3);
        assert_eq!(
            miner.prepare_pending_block(&*client),
            BlockPreparationStatus::NotPrepared
        );
    }

    #[test]
    fn should_not_use_pending_block_if_best_block_is_higher() {
        // given
        let client = TestBlockChainClient::default();
        let miner = miner();
        let transaction = transaction();
        let best_block = 10;
        // when
        let res = miner.import_own_transaction(&client, PendingTransaction::new(transaction, None));

        // then
        assert_eq!(res.unwrap(), ());
        assert_eq!(miner.pending_transactions(best_block), None);
        assert_eq!(miner.pending_receipts(best_block), None);
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            1
        );
    }

    #[test]
    fn should_import_external_transaction() {
        // given
        let client = TestBlockChainClient::default();
        let miner = miner();
        let transaction = transaction().into();
        let best_block = 0;
        // when
        let res = miner
            .import_external_transactions(&client, vec![transaction])
            .pop()
            .unwrap();

        // then
        assert_eq!(res.unwrap(), ());
        // By default we don't reseal on external transactions
        assert_eq!(miner.pending_transactions(best_block), None);
        assert_eq!(miner.pending_receipts(best_block), None);
        // By default we use PendingSet::AlwaysSealing, so no transactions yet.
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            0
        );
        // This method will let us know if pending block was created (before calling that method)
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::Succeeded
        );
        // After pending block is created we should see a transaction.
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            1
        );
    }

    #[test]
    fn should_treat_unfamiliar_locals_selectively() {
        // given
        let keypair = Random.generate();
        let client = TestBlockChainClient::default();
        let mut local_accounts = ::std::collections::HashSet::new();
        local_accounts.insert(keypair.address());

        let miner = Miner::new(
            MinerOptions {
                tx_queue_no_unfamiliar_locals: true,
                ..miner().options
            },
            GasPricer::new_fixed(0u64.into()),
            &Spec::new_test(),
            local_accounts,
        );
        let transaction = transaction();
        let best_block = 0;
        // when
        // This transaction should not be marked as local because our account_provider doesn't have the sender
        let res = miner.import_claimed_local_transaction(
            &client,
            PendingTransaction::new(transaction.clone(), None),
            false,
        );

        // then
        // Check the same conditions as `should_import_external_transaction` first. Behaviour should be identical.
        // That is: it's treated as though we added it through `import_external_transactions`
        assert_eq!(res.unwrap(), ());
        assert_eq!(miner.pending_transactions(best_block), None);
        assert_eq!(miner.pending_receipts(best_block), None);
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            0
        );
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::Succeeded
        );
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            1
        );

        // when - 2nd part: create a local transaction from account_provider.
        // Borrow the transaction used before & sign with our generated keypair.
        let local_transaction = transaction
            .deconstruct()
            .0
            .as_unsigned()
            .clone()
            .sign(keypair.secret(), Some(TEST_CHAIN_ID));
        let res2 = miner.import_claimed_local_transaction(
            &client,
            PendingTransaction::new(local_transaction, None),
            false,
        );

        // then - 2nd part: we add on the results from the last pending block.
        // This is borrowed from `should_make_pending_block_when_importing_own_transaction` and slightly modified.
        assert_eq!(res2.unwrap(), ());
        assert_eq!(miner.pending_transactions(best_block).unwrap().len(), 2);
        assert_eq!(miner.pending_receipts(best_block).unwrap().len(), 2);
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            2
        );
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::NotPrepared
        );
    }

    #[test]
    fn should_reject_local_transaction_with_invalid_chain_id() {
        let spec = Spec::new_test();
        let miner = Miner::new_for_tests(&spec, None);
        let client = TestBlockChainClient::default();
        let chain_id = spec.chain_id();

        // chain_id + 100500 is invalid
        let import = miner.import_claimed_local_transaction(
            &client,
            PendingTransaction::new(transaction_with_chain_id(chain_id + 10500), None),
            false,
        );
        assert_eq!(import, Err(transaction::Error::InvalidChainId));

        // chain_id is valid
        let import = miner.import_claimed_local_transaction(
            &client,
            PendingTransaction::new(transaction_with_chain_id(chain_id), None),
            false,
        );
        assert_eq!(import, Ok(()));
    }

    #[test]
    fn should_prioritize_locals() {
        let client = TestBlockChainClient::default();
        let transaction = transaction();
        let miner = Miner::new(
            MinerOptions {
                tx_queue_no_unfamiliar_locals: true, // should work even with this enabled
                ..miner().options
            },
            GasPricer::new_fixed(0u64.into()),
            &Spec::new_test(),
            HashSet::from_iter(vec![transaction.sender()].into_iter()),
        );
        let best_block = 0;

        // Miner with sender as a known local address should prioritize transactions from that address
        let res2 = miner.import_claimed_local_transaction(
            &client,
            PendingTransaction::new(transaction, None),
            false,
        );

        // check to make sure the prioritized transaction is pending
        assert_eq!(res2.unwrap(), ());
        assert_eq!(miner.pending_transactions(best_block).unwrap().len(), 1);
        assert_eq!(miner.pending_receipts(best_block).unwrap().len(), 1);
        assert_eq!(
            miner
                .ready_transactions(&client, 10, PendingOrdering::Priority)
                .len(),
            1
        );
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::NotPrepared
        );
    }

    #[test]
    fn should_not_seal_unless_enabled() {
        let miner = miner();
        let client = TestBlockChainClient::default();
        // By default resealing is not required.
        assert!(!miner.requires_reseal(1u8.into()));

        miner
            .import_external_transactions(&client, vec![transaction().into()])
            .pop()
            .unwrap()
            .unwrap();
        assert_eq!(
            miner.prepare_pending_block(&client),
            BlockPreparationStatus::Succeeded
        );
        // Unless asked to prepare work.
        assert!(miner.requires_reseal(1u8.into()));
    }

    #[test]
    fn internal_seals_without_work() {
        let spec = Spec::new_instant();
        let miner = Miner::new_for_tests(&spec, None);

        let client = generate_dummy_client(2);

        let import = miner
            .import_external_transactions(
                &*client,
                vec![transaction_with_chain_id(spec.chain_id()).into()],
            )
            .pop()
            .unwrap();
        assert_eq!(import.unwrap(), ());

        miner.update_sealing(&*client, ForceUpdateSealing::No);
        client.flush_queue();
        assert!(miner.pending_block(0).is_none());
        assert_eq!(client.chain_info().best_block_number, 3 as BlockNumber);

        assert!(miner
            .import_own_transaction(
                &*client,
                PendingTransaction::new(transaction_with_chain_id(spec.chain_id()).into(), None)
            )
            .is_ok());

        miner.update_sealing(&*client, ForceUpdateSealing::No);
        client.flush_queue();
        assert!(miner.pending_block(0).is_none());
        assert_eq!(client.chain_info().best_block_number, 4 as BlockNumber);
    }

    #[test]
    fn should_not_fail_setting_engine_signer_without_account_provider() {
        let spec = Spec::new_test_round;
        let tap = Arc::new(AccountProvider::transient_provider());
        let addr = tap.insert_account(keccak("1").into(), &"".into()).unwrap();
        let client = generate_dummy_client_with_spec(spec);
        let engine_signer = Box::new((tap.clone(), addr, "".into()));
        let msg = [1u8; 32].into();
        assert!(client.engine().sign(msg).is_err());

        // should set engine signer and miner author
        client.miner().set_author(Author::Sealer(engine_signer));
        assert_eq!(client.miner().authoring_params().author, addr);
        assert!(client.engine().sign(msg).is_ok());
    }

    #[test]
    fn should_mine_if_internal_sealing_is_enabled() {
        let spec = Spec::new_instant();
        let miner = Miner::new_for_tests(&spec, None);

        let client = generate_dummy_client(2);
        miner.update_sealing(&*client, ForceUpdateSealing::No);

        assert!(miner.is_currently_sealing());
    }

    #[test]
    fn should_not_mine_if_internal_sealing_is_disabled() {
        let spec = Spec::new_test_round();
        let miner = Miner::new_for_tests(&spec, None);

        let client = generate_dummy_client(2);
        miner.update_sealing(&*client, ForceUpdateSealing::No);

        assert!(!miner.is_currently_sealing());
    }

    #[test]
    fn should_not_mine_if_no_fetch_work_request() {
        let spec = Spec::new_test();
        let miner = Miner::new_for_tests(&spec, None);

        let client = generate_dummy_client(2);
        miner.update_sealing(&*client, ForceUpdateSealing::No);

        assert!(!miner.is_currently_sealing());
    }

    #[cfg(feature = "work-notify")]
    #[test]
    fn should_mine_if_fetch_work_request() {
        struct DummyNotifyWork;

        impl NotifyWork for DummyNotifyWork {
            fn notify(&self, _pow_hash: H256, _difficulty: U256, _number: u64) {}
        }

        let spec = Spec::new_test();
        let miner = Miner::new_for_tests(&spec, None);
        miner.add_work_listener(Box::new(DummyNotifyWork));

        let client = generate_dummy_client(2);
        miner.update_sealing(&*client, ForceUpdateSealing::No);

        assert!(miner.is_currently_sealing());
    }

    #[test]
    fn should_set_new_minimum_gas_price() {
        // Creates a new GasPricer::Fixed behind the scenes
        let miner = Miner::new_for_tests(&Spec::new_test(), None);

        let expected_minimum_gas_price: U256 = 0x1337.into();
        miner
            .set_minimal_gas_price(expected_minimum_gas_price)
            .unwrap();

        let txq_options = miner.transaction_queue.status().options;
        let current_minimum_gas_price = txq_options.minimal_gas_price;

        assert!(current_minimum_gas_price == expected_minimum_gas_price);
    }

    #[cfg(feature = "price-info")]
    fn dynamic_gas_pricer() -> GasPricer {
        use ethcore_miner::gas_price_calibrator::{GasPriceCalibrator, GasPriceCalibratorOptions};
        use fetch::Client as FetchClient;
        use parity_runtime::Executor;

        // Don't really care about any of these settings since
        // the gas pricer is never actually going to be used
        let fetch = FetchClient::new(1).unwrap();
        let p = Executor::new_sync();

        GasPricer::new_calibrated(GasPriceCalibrator::new(
            GasPriceCalibratorOptions {
                usd_per_tx: 0.0,
                recalibration_period: Duration::from_secs(0),
            },
            fetch,
            p,
            "fake_endpoint".to_owned(),
        ))
    }

    #[test]
    #[cfg(feature = "price-info")]
    fn should_fail_to_set_new_minimum_gas_price() {
        // We get a fixed gas pricer by default, need to change that
        let miner = Miner::new_for_tests(&Spec::new_test(), None);
        let calibrated_gas_pricer = dynamic_gas_pricer();
        *miner.gas_pricer.lock() = calibrated_gas_pricer;

        let expected_minimum_gas_price: U256 = 0x1337.into();
        let result = miner.set_minimal_gas_price(expected_minimum_gas_price);
        assert!(result.is_err());

        let received_error_msg = result.unwrap_err();
        let expected_error_msg =
            "Can't update fixed gas price while automatic gas calibration is enabled.";

        assert!(received_error_msg == expected_error_msg);
    }
}
